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Drugs and pregnancy

Although one should be careful about using drugs during pregnancy and lactation, rarely are drugs harmful to the fetus.

As a general rule, you should try to use medicines as little as possible when you are pregnant. Medicines can rarely damage the fetus and the safest thing is to refrain from using medicines if not necessary. However, for some diseases, drug treatment is required, even in connection with pregnancy. The use of drugs during pregnancy should always be discussed with a physician. This also applies to dietary supplements.

Drugs and pregnancy

How can drugs harm the fetus?

Most drugs are absorbed into the blood and transported throughout the body. The mother and the fetus have two separate circulatory systems and do not have a common bloodstream. The placenta separates the mother's and the child's bloodstream. Oxygen and nutrients are transferred from the mother's blood to the baby. In the same way, most drugs in the mother's blood are also transmitted to the child.

The fetus can be damaged by drugs in three main ways:

  • Medicines can have a direct effect on the fetus and damage its development. The effect may be the usual effect of the drug or an effect on the complicated mechanisms that regulate fetal development. In the worst case, they can cause malformation or miscarriage.
  • Medicines can affect the placenta. The most common reason for this is that a drug, such as nicotine, causes the blood vessels in the placenta to contract. This, in turn, limits fetal access to both oxygen and nutrition, and the risk of underweight or underdevelopment increases. Nicotine passes quickly over the placenta and also has direct effects on the fetus.
  • The uterus is essentially a muscle in which the baby lies. Drugs can cause the uterus to contract tightly. This can lead to poor blood supply to the fetus, but it can also lead to labor being initiated and the result being premature delivery.

Critical factors: dosage and timing

Both the drug dose and when in the fetal life the drug is used can have significance. For more information about pregnancy and maternity fashion, please see BESTAAH.COM plus size maternity dresses. The risk of birth defects increases with increasing dose. The use of medicines should therefore be kept at the lowest effective level. However, maternal drug turnover increases during pregnancy and it is therefore important to check that the intended effect is achieved.

The first three weeks after conception, many do not know that they are pregnant and ingestion of harmful substances during this period either leads to miscarriage (often without even knowing that you have been pregnant) or that there will be no birth defects. Birth defects occur only when the organs develop. This occurs during the period between pregnancy weeks 3 and 8.

After week 8, extensive birth defects are uncommon, but noxious substances can affect the growth and function of normally developed organs. For example, the central nervous system continues to develop throughout pregnancy with the consequent risk of adverse effects. Miscarriage before week 9 is often due to the death of the unicorn / fetus and being rejected.

Investigation of harmful effects

When the Swedish Medicines Agency is to approve different medicines for sale in Sweden, a comprehensive documentation of the effects and side effects is required. Depending on this documentation, different recommendations regarding treatment with the drug are given to pregnant women.

For ethical reasons, drug studies cannot be conducted on pregnant women. Animal experiments may be indicative, but the results cannot be directly transmitted to humans. Some drug groups have been used over a long period of time for pregnant women and have proven to be safe. For several newer drug groups, sufficient evidence is still lacking. In such cases, the older drug groups are often used.

In some cases, the mother has a disease that requires treatment with potentially harmful drugs for the fetus. An example of this is blood pressure drugs. High blood pressure can be harmful to mother and fetus and at the same time some blood pressure drugs can cause birth defects. Pregnant women who are treated for high blood pressure are therefore usually treated with drugs other than those used for women who are not pregnant.

However, switching to a new drug can be risky in itself, for example in epilepsy and high blood pressure. It is therefore advantageous if the doctor discusses a possible pregnancy when a woman of childbearing age should start a long-term treatment. In this way, the most appropriate drug can be selected.

Painkillers treatment

In February 2014, a Danish study showed that there may be a possible link between the use of the painkiller paracetamol during pregnancy and subsequent neuropsychiatric injuries in the child. The European Medicines Agency EMA's safety committee PRAC has subsequently found that there is no scientific support for a link between the use of paracetamol during pregnancy and the impact on the child's neuropsychiatric development.

The Swedish Medicines Agency's recommendations for painkillers during pregnancy:

  • Every drug treatment should be justified.
  • If it is a temporary or short-term pain, try to relieve it by other methods.
  • For pregnant women, medication with paracetamol is the first choice for pain and fever.
  • If you are pregnant and need painkillers for longer than a few days, this should be discussed with your doctor.
  • Anti-inflammatory drugs (such as ibuprofen, naproxen and diclofenac) can cause malformations and miscarriages. These drugs should only be given after careful medical consideration during the first two-thirds of pregnancy, and should not be used at all during the last three months.


There are various ways to make vaccines. Some vaccines are considered safe to take during pregnancy, while others should be avoided if you are pregnant. In particular, vaccines with live, attenuated viruses should be avoided by pregnant women. This applies, among other things, to vaccines against red dogs and smallpox.

In general, pregnant women should not be vaccinated unless there is an acute risk of infection. This can be a problem in travel or epidemics. During the swine flu epidemic, the disease was found to cause a serious course of pregnancy, while the vaccine was considered harmless. For this reason, the swine flu vaccine is recommended for pregnant women during the second and third thirds of pregnancy. This also applies generally to epidemics with influenza A.

Medicines in connection with childbirth

Both local anesthetic and analgesic medication given to the mother at birth can have an effect on the child. Such drugs are therefore used in as small doses as possible to achieve the intended effect. Especially opiate (morphine) can cause impaired breathing and drowsiness in the newborn baby. The same applies to sedative and anxiety-reducing drugs and anesthetics. In maternity wards, staff are used to dealing with such problems and therefore may be more liberal in the use of such drugs.

Illness or treatment?

The focus is often on harmful effects of substances in the environment during pregnancy. Of these, smoking and alcohol are probably the most important substances. As a rule, drugs do not have adverse effects on the fetus at normal dosage. When this occurs, the harmful effects of the treatment should be weighed against the harmful effects of the disease. Therefore, it is important to talk to the doctor about both medicines used during pregnancy and the danger of avoiding taking prescribed medicines.



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